(1) Field of the Invention
The present invention relates to water vehicles, and more particularly to methods and apparatus for the electrical grounding of water vehicles.
(2) Brief Description of Prior Developments
Many high speed water vehicles are built with hulls comprised of nonconductive materials such as composite fiberglass and resin materials and wood. Electrical grounding of on board RF transmitters and on board electrical equipment can, therefore, require particular adaptations on the hull which may be expensive and time consuming to install. For example, in some cases a partial metal liner is installed on nonconductive hulls to facilitate grounding.
In other situations, the difficulty in grounding water vehicles with nonconductive hulls may limit communications capabilities on such vehicles. For example, many smaller high speed water vehicles with nonconductive hulls make use of VHF RF transmitters even though such transmitters are limited in terms of range. Although the extended range HF RF transmitters may be desirable for many such vessels, grounding requirements may limit the use of HF RF transmitters on such vessels.
Referring to FIG. 1, a prior art arrangement for grounding an RF transmitter is shown in which a boat 10 equipped with a transmitter 12 and an outrigger 14 is moving in a forward direction 16. The outrigger mounting 14 includes a lower horizontal beam 18 and an upper angled beam 20. There is a lower pulley 22 on the lower horizontal beam 18 and an upper pulley 24 mounted on the outer end of the upper-angle beam 20. An RF ground wire shown generally at numeral 26 extends from the RF transmitter 12. This RF ground wire 26 includes an outward length 28 which extends from the RF transmitter 12 to the upper pulley 24. From the pulley 24 to the lower pulley 22 the RF ground wire 26 includes a vertical length 30. Extending in a rearward direction 32 which is generally opposite from the forward direction of the boat 10 there is a rearward length 24 of the RF ground wire 26. At the terminal end of this rearward length 34 there is a rearward terminal weight 36 which is usually able to maintain the rearward length 34 of the RF ground wire 26 in a body of water 38 at low speeds. At higher boat speeds, however, the rearward terminal weight 36 and the rearward length 34 of the RF ground wire 26 will often begin moving in an outward and upward skipping motion 40 so that the rearward length will move out of the water as at 34xe2x80x2 and the rearward terminal weight will similarly move to 36xe2x80x2.
The velocity of the water vehicle containing the RF transmitter source is xe2x80x9cspeed limitedxe2x80x9d. Typically, under normal wave and weather conditions the water vehicle velocity range is only 4 to 7 knots. Under more adverse wave and weather conditions the water vehicle velocity must be reduced to maintain continuous contact with the RF ground conductor and water. The speed limitation of the water vehicle is created by a combination of the forward velocity of the water vehicle and the drag forces imposed on the weighted RF ground conductor increase causing the weighted RF ground conductor to lose continuous contact with the water. The loss of continuous contact or xe2x80x9cskipping actionxe2x80x9d of the RF ground conductor wire causes loss of signal strength, increases interference with other electronics on the water vehicle, and can cause data collection loss during antenna calibration.
An improved method and apparatus for grounding electrical apparatus on water vehicles is, therefore, needed.
The present invention is a high speed RF ground device for water vehicles. The device includes an elongated electrical conductive section and an elongated rope for increasing water resistance positioned in an adjacent relation to the elongated electrical conductive section.
The present invention also encompasses a method for grounding an RF circuit on a water vehicle which includes the step of connecting an elongated grounding devise which includes an electrical conductive section and an elongated rope for increasing water resistance section to the RF circuit. The water vehicle is then caused to move in a forward direction. The elongating grounding device is then positioned to extend rearwardly from the water vehicle.